Effects of the phylogeny and seed traits on germination of Polygonaceae species from Subtropical Forest, Southeast China.

Seed germination directly influences seeding survival. Phylogenetically related species often exhibit similar germination traits; however, several environmental factors also play important roles in determining germination. In this study, we tested inter-specific variability in seeds and investigated relations between germination responses, seed morphology, and phylogenetic relatedness in 9 species of Polygonaceae. Seed dimensions (length, width, and height) were examined using a Stereo Microscope equipped with a microscope camera. Water permeability was assessed by measuring the mass of three replicates of 25 seeds. Seeds were tested at five different alternating temperature regimes: 5/10, 10/20, 20/30, 25/35, and 35/40 °C and under two different conditions: 24 h darkness (dark treatment) and 12 h light/12 h darkness (light treatment) and light regimes. The findings highlighted significant differences in the seed morphology, water uptake, and germination behavior. Some species exhibited physiological dormancy while other responded readily to light and temperature. Seed size was positively correlated with germination performance, while the seed morphology distance matrix was not correlated to phylogenetic distances. These findings suggest that while phylogeny is an important factor in determining a role in seed traits, environmental cues play a more intense role in the evolution of seed traits in Polygonaceae. [ABSTRACT FROM AUTHOR]